Considerable market demand exists for a decorative laminate structure which can withstand moderate to severe heat. For example, heat resistant decorative laminates could be used as kitchen counter tops, laboratory tables, desks, and other similar work surfaces. The surface of these decorative laminates desirably should be able to withstand the heat of objects removed from an oven or open flame, as well as burning cigaretts, cigars and matches. In addition to providing the desired decor and heat resistivity, the subject decorative laminate also should provide the necessary structural integrity for the work surface and should be available at a cost competitive with other decorative laminates.
In response to the potential market demand, a considerable amount of research and development work has been devoted to developing a decorative laminate with the above described characteristics. Several structures have been developed which incorporate a layer of aluminum intermediate the substrate and the decorative laminate layer. The aluminum layer in this structure is intended to rapidly dissipate heat placed on the surface of the laminate, thereby avoiding damage or discoloration to the structure. Although decorative laminates of this type are theoretically feasible, they have proved difficult and uneconomical to manufacture. Specifically, there are many technical problems associated with gluing the aluminum foil layer to the substrate, and then gluing the decorative laminate to the foil. Even if the technical problems can be overcome, the product must be run along a first production line to adhere the foil to the substrate and then along a second production line to adhere the decorative laminate to the foil. The manufacturing process is both time consuming and costly.
U.S. Pat. No. 4,272,581 which issued to Cooley et al on June 9, 1981 and which is assigned to the assignee of the subject invention, is directed to a heat resistant decorative laminate where a substrate member is directly adhered to a decorative plastic film by an adhesive having aluminum powder dispersed therein. The aluminum powder, which comprises about ten to fifteen weight percent of the total adhesive mixture, contributes to heat dispersion. The decorative plastic film of the laminate described in U.S. Pat. No. 4,272,581 preferably is over-coated with a layer of clear material which further protects the resultant product. The decorative laminate disclosed in U.S. Pat. No. 4,272,581 provides economic advantages in that the heat dissipating aluminum and the adhesive for the decorative layer can be applied in a single application. Although the above described product performs well in many temperature ranges, it is desired to provide a product with an improved ability to resist moderate to extreme heat.
U.S. Pat. No. 3,476,585 which issued to Fraser et al is directed to the metal coating of wood substrates with an improved adhesion between the wood substrate and the metal. More particularly the wood is first coated with a mixture of phenol formaldahyde and epichlorohydrin polyamide resin. The resin is allowed to dry on the wood prior to coating the wood with the metal. A metal layer of bronze, steel, aluminum, copper, nickel, cromium or zinc then is applied over the coated wood by oxyacetylene flame spraying. Although this reference may provide enhanced adhesion, the metal coating process would appear to require at least as much production time as the previously described prior art procedures. U.S. Pat. No. 3,476,585 suggests that the metal coating is continuous, and does not suggest the application of subsequent coating, such as decorative laminates, on top of the metal.
A similar metallic coating technique is described in U.S. Pat. No. 4,330,575 which issued to Litchfield et al. In this latter patent, however, the coating material is an admixture of 20 to 40% by volume of particles of a nickel base alloy or cobalt base alloy each containing chromium and aluminum, with the balance of the admixture being hollow glass particles which are coated with a nickel base alloy or cobalt base alloy containing chromium or aluminum. This coating admixture, as described in U.S. Pat. No. 4,330,575, is applied to certain parts of gas turbines by plasma spraying techniques to provide a thermal barrier which is resistant to conditions of oxidation and thermal shock. U.S. Pat. No. 4,330,575 does not suggest application of the coating material to a wood substrate. Additionally, this reference only is directed to a coating mixture containing the nickel or cobalt base alloys and coated hollow glass particles. The reference does not suggest a decorative laminate for a wood substrate including metallic layers applied by plasma arc spraying techniques.
A metal coating on wood also is shown by U.S. Pat. No. 3,932,143 which issued to Marshall et al. More particularly U.S. Pat. No. 3,932,143 is directed to a wood base roofing material which is coated with at least one continuous metallic layer to prevent decay and to resist flame. The one or more metallic layers, as described in U.S. Pat. No. 3,932,143 are applied by flame spraying techniques. This reference does not suggest additional layers to create a decorative heat resistant laminate.
U.S. Pat. No. 4,101,698, which issued to Dunning et al is directed to a transfer laminate for use in bumpers of automobiles. The laminate shown in U.S. Pat. No. 4,101,698 includes a microscopically discontinuous layer of metal applied by vacuum deposition to an elastomeric film. The reference, however, does not suggest the application of discontinuous metallic layers to wood substrates to improve heat resistivity.
In view of the above, it is an object of the subject invention to provide a decorative laminate on a wood or wood by product substrate with an enhanced ability to resist heat.
It is another object of the subject invention to provide a heat resistant decorative laminate which overcomes the adhesion problems typically encountered in adhering a metallic foil layer to a wood substrate.
It is an object of the subject invention to provide a heat resistant decorative laminate which overcomes the problems of adhering the decorative layer to a metallic layer for dissipating heat.
It is a further object of the subject invention to provide a heat resistant decorative laminate with a metallic layer which can be manufactured efficiently and at a low cost.